Mindfulness-based interventions (MBIs) are increasingly being implemented in school settings for children and adolescents. Although positive outcomes have been documented for youth, less is known about the constructs of mindfulness (e.g., intention, attention, awareness, nonjudgement) that contribute to positive outcomes or how they are measured. Systematically identifying measures will facilitate improved understanding of what constructs of mindfulness are captured. The current study systematically reviewed literature to identify child and adolescent mindfulness measures from 2000 to 2021. Multiple search engines including PsycTest, PsycInfo, Psycarticles, NCBI, US National Library of Medicine, National Institutes of Health, APA PsychTest, and Google Scholar were used. Results of the current study describe a variety of measures to capture mindfulness and may be useful for researchers and practitioners implementing and/or evaluating mindfulness practices in schools. Eleven youth self-report measures designed for youth 5 to 18 years old were identified. A little more than half measured mindfulness multidimensionally (multiple constructs of mindfulness). Constructs commonly included on measures were attention, awareness, and assessment of one's own internal and external experiences. Descriptive information (e.g., target age range, description of mindfulness constructs) is provided for each measure. Future directions include continued investigation of validity, particularly content validity for youth mindfulness measures, and examining how the use of multiple methods and/or raters could contribute to an understanding of youth's mindfulness experience. Additional implications for the field of school psychology and limitations of the study are discussed.